The present invention generally relates to a shaft seal, and, more specifically, to a shaft seal that provides a high resistance to infiltration of contaminants from one side of the shaft seal to the other side of the shaft seal.
Many mechanical devices have shafts that extend from a housing. Conventionally, the housing is filled with fluid or lubricant. The shafts which pass through the housing wall drive or may be driven by an external component. A gear set or other mechanical device that modifies the rotational energy, torque or speed supplied from one shaft to another shaft is located inside of the housing. These devices must be fluidly sealed from the external environment to ensure that contaminants do not enter the housing. Also, the housing is sealed from the inside so that fluid does not leak from the housing to the external environment. It is difficult to seal the housing with the rotating shaft since space is required between the shaft and housing to allow for rotation. Fluid seals are positioned between the shaft and the wall of the housing to aid in fluidly sealing this space. Typically, these seals are donut like with a through bore. The inner diameter surface of the seal presses against the seal area of the shaft. The outer diameter surface of the seal engages an aperture formed in the housing wall. As a result, the shaft rotates and slides against the fluid seal. The fluid seal presses against the seal area of the shaft and against the housing wall to form a barrier between the inside of the housing and the external environment.
While such devices serve well to seal one side of the seal area from the other, drawbacks exist by virtue of spacing between the seal and shaft. Specifically, the natural spacing that exists between the shaft and the seal area can allow a small amount of contaminants to pass from one side of the seal to the other. Although small in quantity, these contaminants can substantially increase the amount of wear between the seal and shaft. Also, the matter can damage internal components within the housing. In addition, the exterior side of the seal is typically exposed to the outside environment which often contains elements detrimental or damaging to the seal such as sunlight, moisture, dust, debris or other airborne materials. The present invention was developed in light of these and other drawbacks.
To address these and other drawbacks, the present invention provides a multiple shaft seal arrangement positioned between the shaft and the inside diameter of an aperture in the housing wall. The multiple shaft seal arrangement includes a disc mounted to the outside diameter of the shaft. The disc extends radially outward to a position spaced from the inside diameter of the aperture. One side of the disc faces the external environment. A face seal is mounted to an opposite side of the disc. A second disc extends from the inside diameter of the aperture to a position spaced from the outside diameter of the shaft. The face seal abuts the second disc to prohibit debris from passing from one side of the multiple shaft seal arrangement to the other side. A seal is attached to the second disc and abuts the outside diameter of the shaft. Accordingly, the multiple shaft seal arrangement prohibits particulate matter and other debris from passing from one side of the wall to the other side.
In another aspect, a speed reducer with a housing includes an aperture in a housing wall. A shaft passes through the aperture. A multiple shaft seal arrangement is positioned between the shaft and the wall defined by the aperture. The multiple shaft seal arrangement includes a disc mounted to the outside diameter of the shaft. The disc extends radially outward to a position spaced from the inside diameter of the aperture. One side of the disc faces an external environment of the housing. A face seal is mounted to an opposite side of the disc. A second disc extends from the inside diameter of the aperture in a direction radially toward the shaft. The face seal presses against the second disc. A seal is attached to the second disc and presses against the outside diameter of the shaft.
In another aspect, a method is disclosed to position a multiple shaft seal arrangement between the wall defined by an inside diameter of an aperture and the outside diameter surface of a shaft. The method utilizes the following steps. The shaft is positioned in the aperture. Next, a seal is mounted to the inside diameter of the aperture. A face seal is then attached to a side of a flinger and the flinger/face seal assembly is mounted to the shaft such that the assembly rotates with the shaft and the face seal presses against the seal.
Further areas of applicability of the present invention will become apparent from the below detailed description. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.